By passions we are to understand here motions of the sensitive appetite in man which tend towards the attainment of some real or apparent good, or the avoidance of some evil. The more intensely the object is desired or abhorred, the more vehement is the passion. St. Paul thus speaks of them: "When we were in the flesh, the passions of sin, which were by the law, did work in our members, to bring forth fruit unto death" (Rom., vii, 5). They are called passions because they cause a transformation of the normal condition of the body and its organs which often appears externally. It may also be noted that there is in man a rational appetite as well as a sensitive appetite. The rational appetite is the will; and its acts of love, joy, and sorrow are only called passions metaphorically, because of their likeness to the acts of the sensitive appetite. They are classified by St. Thomas and the Schoolmen as follows: The sensitive appetite is twofold, concupiscible and irascible, specifically distinct because of their objects. The object of the concupiscible is real or apparent good, and suitable to the sensitive inclination. The object of the irascible appetite is good qualified by some special difficulty in its attainment. The chief passions are eleven in number:

Six in the concupiscible appetite — namely, joy or delight, and sadness, desire and aversion or abhorrence, love and hatred — and

five in the irascible — hope and despair, courage and fear, and anger.

To explain the passions in their relation to virtue it is necessary to consider them first in the moral order. Some moralists have taught that all passions are good if kept under subjection, and all bad if unrestrained. The truth is that, as regards morality, the passions are indifferent, that is, neither good nor bad in themselves. Only in so far as they are voluntary do they come under the moral law. Their motions may sometimes be antecedent to any act of the will; or they may be so strong as to resist every command of the will. The feelings in connexion with the passions may be lasting, and not always under the control of the will, as for example the feelings of love, sorrow, fear, and anger, as experienced in the sensitive appetite; but they can never be so strong as to force the consent of our free will unless they first run away with our reason.

These involuntary motions of the passions are neither morally good nor morally bad. They become voluntary in two ways:

by the command of the will, which can command the inferior powers of the sensitive appetite and excite its emotions;

by nonresistance, for the will can resist by refusing its consent to their promptings, and it is bound to resist when their promptings are irrational and inordinate. When voluntary, the passions may increase the intensity of the acts of the will, but they may also lessen their morality by affecting its freedom.

In regard to virtue the passions may be considered in the three stages of the spiritual life:

first, its acquisition;

secondly, its increase;

thirdly, its perfection.

When regulated by reason, and subjected to the control of the will, the passions may be considered good and used as means of acquiring and exercising virtue. Christ Himself, in whom their could be no sin nor shadow of imperfection, admitted their influence, for we read that He was sorrowful even unto death (Mark, xiv, 34), that He wept over Jerusalem (Luke, xix, 41), and at the tomb of Lazarus He groaned in the spirit, and troubled Himself (John, xi, 33). St. Paul bids us rejoice with them that rejoice, and weep with them that weep (Rom., xii, 15). The sensitive is given to man by God, and therefore its acts have to be employed in His service. Fear of death, judgement, and hell prompts one to repentance, and to the first efforts in acquiring virtue. Thoughts of the mercy of God produce hope, gratitude, and correspondence. Reflections on the sufferings of Christ moves to sorrow for sin, and to compassion and love for Him in His sufferings. The moral virtues are to regulate the passions and employ them as aids in the progress of spiritual life. A just man at times experiences great joy, great hope and confidence, and other feelings in performing duties of piety, and also great sensible sorrow, as well as sorrow of soul, for his sins, and he is thus confirmed in his justice. He can also merit constantly by restraining and purifying his passions. The saints who reached the exalted state of perfection, have retained their capacity for all human emotions and their sensibility has remained subject to the ordinary laws; but in them the love of God has controlled the mental images which excite the passions and directed all their emotions to His active service. It has been justly said that the saint dies, and is born again: he dies to an agitated, distracted and sensual life, by temperance, continency, and austerity, and is born to a new and transformed life. He passes through what St. John calls "the night of the senses", after which his eyes are opened to a clearer light. "The saint will return later on to sensible objects to enjoy them in his own way, but far more intensely than other men" (H. Joly, "Psychology of the Saints", 128). Accordingly we can understand how the passions and the emotions of the sensitive appetite may be directed and devoted to the service of God, and to the acquisition, increase, and perfection of virtue.

All admit that the passions, unless restrained, will carry a man beyond the bounds of duty and honesty, and plunge him into sinful excesses. Unbridled passions cause all the moral ruin and most of the physical and social evils that afflict men. There are two adverse elements in man contending for the mastery, and designated by St. Paul as "the flesh" and "the spirit" (Gal., v, 17). These two are often at variance with each other in inclinations and desires. To establish and preserve harmony in the individual, it is necessary that the spirit rule, and that the flesh be made obedient to it. The spirit must set itself free from the tyranny of the passions in the flesh. It must free itself by the renunciation of all those unlawful things which our lower nature craves, that right order may be established and preserved in the relations of our higher and lower nature. The flesh and its appetites, if allowed, will throw everything into confusion and vitiate our whole nature by sin and its consequences. It is therefore man's duty to control and regulate it by reason and a strong will aided by God's grace.